Effects of sustainable agronomic intensification in a forage production system of perennial grass and silage corn on nutritive value and predicted milk production of dairy cattle.

The objectives were to determine the effects of incrementally applied improved nutrient management, alternative cropping practices, and advanced production technologies in a dual forage system of perennial grass and silage corn on nutrient composition and in vitro ruminal fiber digestibility of the forages and, using these data as inputs into the Cornell Net Carbohydrate and Protein System, to predict milk production, indicators of nitrogen (N) utilization, and N excretion of dairy cattle. Farm management systems (farmlets) included a conventional system with whole manure slurry broadcast to a late maturing corn hybrid and grass harvested with 5 cuts per year (F1); improved nutrient management with a separated manure system where the sludge was applied to corn and the liquid was applied to grass (F2); improved nutrient management and alternative cropping practices with separated manure, an early maturing corn hybrid interseeded with a relay winter cover crop, and grass harvested with 3 cuts per year (F3); and improved nutrient management and alternative cropping practices combined with advanced production technologies that included irrigation and a nitrification inhibitor (F4). The field trial was a randomized complete block design over 2 yr with 4 blocks each divided into grass and corn, 4 subplots within each block for each crop, and 2 replicates within each subplot. Diets were formulation with 60% forage and 40% concentrate where the grass and corn as silage was proportional to yield for land allocations of grass and corn of 80:20, 60:40, 40:60, and 20:80. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc.). The intensified management systems (F2, F3, and F4) increased the crude protein (CP) concentration of corn with no effects on starch concentration [32.1% dry matter (DM)] compared with the conventional system (F1). Decreasing cuts of grass from 5 to 3 reduced the CP concentration in the spring harvest (15.8% vs. 12.5% DM), and increased fiber concentration and reduced digestibility in the spring, summer, and fall harvests. A common concentrate was formulated for the conventional farmlet and then combined with the forages for each farmlet within each land allocation. Forages grown under intensified management to improve N capture increased the CP concentration of the diets. However, reducing the number of cuts of grass from 5 to 3, combined with the corn and relay crop to increase yield, reduced milk production across all land allocations. To complement the nutritive value of the forages grown under each management system and land allocation, the concentrates were reformulated, which reduced dietary CP, improved the indicators of N utilization (e.g., milk urea N and milk N efficiency), reduced N excretion, and improved milk yield with no differences among the farmlets. Increasing land allocated to corn supported higher milk yield at lower dietary CP concentrations (16.5% vs. 15.4% DM) with improved milk N efficiency and lower N excretion. Intensified agronomic management increased the CP of the combined forages decreasing the need for supplemental CP in the concentrate and could reduce the importation of feed N to the farm.

Invited review: Current enteric methane mitigation options.

Ruminant livestock are an important source of anthropogenic methane (CH4). Decreasing the emissions of enteric CH4 from ruminant production is strategic to limit the global temperature increase to 1.5°C by 2050. Research in the area of enteric CH4 mitigation has grown exponentially in the last 2 decades, with various strategies for enteric CH4 abatement being investigated: production intensification, dietary manipulation (including supplementation and processing of concentrates and lipids, and management of forage and pastures), rumen manipulation (supplementation of ionophores, 3-nitrooxypropanol, macroalgae, alternative electron acceptors, and phytochemicals), and selection of low-CH4-producing animals. Other enteric CH4 mitigation strategies are at earlier stages of research but rapidly developing. Herein, we discuss and analyze the current status of available enteric CH4 mitigation strategies with an emphasis on opportunities and barriers to their implementation in confined and partial grazing production systems, and in extensive and fully grazing production systems. For each enteric CH4 mitigation strategy, we discuss its effectiveness to decrease total CH4 emissions and emissions on a per animal product basis, safety issues, impacts on the emissions of other greenhouse gases, as well as other economic, regulatory, and societal aspects that are key to implementation. Most research has been conducted with confined animals, and considerably more research is needed to develop, adapt, and evaluate antimethanogenic strategies for grazing systems. In general, few options are currently available for extensive production systems without feed supplementation. Continuous research and development are needed to develop enteric CH4 mitigation strategies that are locally applicable. Information is needed to calculate carbon footprints of interventions on a regional basis to evaluate the impact of mitigation strategies on net greenhouse gas emissions. Economically affordable enteric CH4 mitigation solutions are urgently needed. Successful implementation of safe and effective antimethanogenic strategies will also require delivery mechanisms and adequate technical support for producers, as well as consumer involvement and acceptance. The most appropriate metrics should be used in quantifying the overall climate outcomes associated with mitigation of enteric CH4 emissions. A holistic approach is required, and buy-in is needed at all levels of the supply chain.

Feeding diets varying in forage proportion and particle length to lactating dairy cows: I. Effects on ruminal pH and fermentation, microbial protein synthesis, digestibility, and milk production.

Physically effective neutral detergent fiber (peNDF) content of dairy cow diets was modified by varying the theoretical chop length of alfalfa silage and forage:concentrate (F:C) ratio, and effects on nutrient intakes, ruminal fermentation, site and extent of digestion, microbial protein synthesis, and milk production were evaluated. Estimates of dietary peNDF contents were compared with recommendations, and predictions of ruminal pH from peNDF and the recently developed physically adjusted neutral detergent fiber (paNDF) system were compared with observed pH. The experiment was designed as a triple 4 × 4 Latin square using 12 mid-lactating dairy cows with 4 intact, 4 ruminally cannulated, and 4 ruminally and duodenally cannulated cows. Site and extent of digestion and microbial protein synthesis were measured in a single 4 × 4 Latin square. Treatments were a 2 × 2 factorial arrangement; 2 forage particle lengths (FPL) of alfalfa silage (short and long) were combined with low (35:65) and high (60:40) F:C ratios [dry matter (DM) basis]. The peNDF contents were determined by multiplying the proportion (DM basis) of total mixed ration retained on 2 (8 and 19 mm; peNDF8.0) or 3 (1.18, 8, and 19 mm; peNDF1.18) sieves of the Penn State Particle Separator by the neutral detergent fiber content of the diet. The dietary peNDF contents ranged from 10.7 to 17.5% for peNDF8.0 or from 23.1 to 28.2% for peNDF1.18. Interactions between F:C ratio and FPL content were few. Increasing peNDF content of diets by increasing F:C ratio decreased DM intake, milk yield, and milk protein yield, whereas apparent total-tract DM digestibility and milk efficiency improved. Increasing F:C ratio improved ruminal pH status but decreased total volatile fatty acid concentration and microbial protein synthesis. Increasing peNDF content of diets via dietary FPL increased mean ruminal pH, but did not affect DM intake, total-tract digestibility, or milk production. The results indicate that feeding dairy cows a low F:C diet helps increase DM intake, milk production, and microbial protein synthesis, but may adversely affect feed digestibility and milk efficiency due to increased risk of subacute ruminal acidosis. Increased FPL improved ruminal pH status, but had minimal effects on feed intake, ruminal fermentation, nutrient digestibility, and milk production. The results indicate a trade-off between reducing the risk of subacute ruminal acidosis and maximizing ruminal fermentation, feed digestibility, and milk production of dairy cows. The paNDF model showed improvement in the predictability of ruminal pH over the peNDF model, but the accuracy of predictions varied depending upon the diet and ruminal fermentation variables considered in the equations.

3-Nitrooxypropanol supplementation had little effect on fiber degradation and microbial colonization of forage particles when evaluated using the in situ ruminal incubation technique.

3-Nitrooxypropanol (3-NOP) is an investigational compound that acts as an enzyme inhibitor to decrease ruminal methanogenesis. We hypothesized that when feeding 3-NOP to cattle fed a high-forage diet, H2 would accumulate in the rumen, which could suppress microbial colonization of feed particles and fiber degradation. Therefore, the study investigated the effects of supplementing a high-forage diet with 3-NOP on ruminal fiber degradability and microbial colonization of feed particles using the in situ technique. Eight ruminally cannulated beef cattle were allocated to 2 groups (4 cattle/group) in a crossover design with 2 periods and 2 dietary treatments. The treatments were control (basal diet) and 3-NOP (basal diet supplemented with 3-NOP, 150 mg/kg of dry matter). The basal diet consisted of 45% barley silage, 45% chopped grass hay, and 10% concentrate (dry matter basis). Samples of dried, ground barley silage and grass hay were incubated in the rumen of each animal for 0, 4, 12, 24, 36, 48, 96, 120, 216, and 288 h to determine neutral detergent fiber (NDF) degradation kinetics. An additional 2 bags were incubated for 4 and 48 h to evaluate the bacterial community attached to the incubated forages. Dietary supplementation of 3-NOP decreased (-53%) the dissolved methane concentration and increased (+780%) the dissolved H2 concentration in ruminal fluid, but did not substantially alter in situ NDF degradation. The addition of 3-NOP resulted in a decrease in the α-diversity of the microbial community with colonizing communities showing reduced numbers of amplicon sequence variants and phylogenetic diversity compared with control diets. Principal coordinate analysis plots indicated that forages incubated in animals fed 3-NOP resulted in highly specific changes to targeted microbes compared with control diets based on unweighted analysis (considering only absence and presence of taxa), but did not alter the overall composition of the colonizing community based on weighted UniFrac distances; unchanged relative abundances of major taxa included phyla Bacteroidetes, Firmicutes, and Fibrobacteres. The effect of 3-NOP on colonizing methanogenic microbes differed depending upon the forage incubated, as abundance of genus Methanobrevibacter was decreased for barley silage but not for grass hay. In conclusion, 3-NOP supplementation of a high-forage diet decreased ruminal methanogenesis and increased dissolved H2 concentration, but had no negative effects on ruminal fiber degradation and only minor effects on relative abundances of the major taxa of bacteria adhered to forage substrates incubated in the rumen.

Liquid hot water treatment of rice straw enhances anaerobic degradation and inhibits methane production during in vitro ruminal fermentation.

Liquid hot water (LHW) treatment can be used to disrupt the fiber structure of rice straw. This in vitro ruminal batch culture study investigated the effect of LHW treatment on feed degradation, methane (CH4) production, and microbial populations. Rice straw was treated by LHW, and in vitro ruminal fermentation was performed using an automatic system with 72 h of incubation. Scanning electron microscopy showed that LHW treatment disrupted the physical structure of rice straw. Liquid hot water treatment decreased neutral detergent fiber and hemicellulose contents of the rice straw and increased neutral detergent solubles, water-soluble carbohydrates, and arabinose contents. Liquid hot water treatment increased dry matter degradation and volatile fatty acid concentration and decreased the acetate:propionate ratio, CH4 production, hydrogen accumulation, neutral detergent fiber degradation, and populations of protozoa, fungi, and cellulolytic bacteria. In summary, LHW treatment disrupted the cellulose-hemicellulose-lignin structure matrix of rice straw, leading to increased substrate degradability and decreased CH4 production. Therefore, the LHW treatment is a potential strategy to improve the nutritive value of forage such as rice straw and decrease the CH4 emissions in ruminants.

The effect of diet of the donor cows on in vitro measurements of methane production from wheat and corn incubated in various forage-to-grain ratios.

BACKGROUND: Supplementation of ruminant diets with wheat and corn grains influences ruminal fermentation. In vitro fermentation is a methodology that can be used to screen feeds for their potential to produce enteric methane. However, there is evidence that the diet of the donor cows could impact the results of in vitro analysis. This research investigated the in vitro fermentation of wheat and corn grain when incubated in ruminal fluid from cows fed different grain types and different forage-to-grain ratios. RESULTS: The type of grain fed to the donor cows, as well as forage-to-grain ratio, affected the outcome of fermentation of wheat and corn grain. Differences in methane production (MP) between grains were only observed when incubated with ruminal fluid adapted to each specific grain type. Increasing proportions of wheat but not of corn decreased in vitro MP in a linear manner compared with MP produced from forage only. CONCLUSIONS: Wheat grain has a greater in vitro antimethanogenic effect than corn. However, to detect the different fermentations between wheat and corn, grains should be incubated in ruminal fluid from cows adapted to that specific grain type. © 2019 Society of Chemical Industry.

Treatment of feces from beef cattle fed the enteric methane inhibitor 3-nitrooxypropanol.

The study evaluated the residual effect of the known enteric methane inhibitor 3-nitrooxypropanol (3NOP) on anaerobic digestion of cattle feces (feces) in a CH4 potential batch test and two consecutive runs of an anaerobic leach bed reactor at a solids retention time of 40 days. The feces used in this study were collected from beef cattle fed forage- (backgrounding) or grain- (finishing) based diets supplemented with 3NOP in feedlot and metabolism studies. The results showed that CH4 yields were not significantly different from treatments using control feces and feces collected from cattle fed a diet supplemented with 3NOP in both CH4 potential and leach bed studies. Spiking feces with 200 mg 3NOP kg-1 dry matter decreased CH4 production rate by 8.0-18.1% estimated from the Gompertz equation, increased the lag phase time (0.4-3.4 d) in all the treatments, while there was no significant difference in the overall CH4 yield. Results from this study showed that 3NOP can be used as an effective enteric CH4 inhibitor with no residual effect on anaerobic digestion.

Urea plus nitrate pretreatment of rice and wheat straws enhances degradation and reduces methane production in in vitro ruminal culture.

BACKGROUND: Urea pretreatment of straw damages fiber structure, while nitrate supplementation of ruminal diets inhibits enteric methane production. The study examined the combined effects of these treatments on ruminal substrate biodegradation and methane production using an in vitro incubation system. Rice and wheat straws were pretreated with urea (40 g kg-1 straw dry matter, DM) and urea + ammonium nitrate (34 + 6 g kg-1 dry matter (DM), respectively), and each straw (control, urea, urea+nitrate) was used in batch culture incubations in three replications (runs). RESULTS: Urea pretreatment increased (P < 0.05) neutral-detergent solubles (NDS) content (+17%) and in vitro DM degradation of rice straw, in comparison with control. Urea+nitrate pretreatment of rice and wheat straws had higher (P < 0.05) NDS content, in vitro DM degradation and propionate molar proportion, and lower (P < 0.05) acetate:propionate ratio and lower methane production with a decline of methanogens, in comparison to control. CONCLUSIONS: Urea+nitrate pretreatment combines positive effects of urea pretreatment and nitrate supplementation, and can be a potential strategy to improve ruminal biodegradation, facilitate propionate production and reduce methane production from lignified straws. © 2018 Society of Chemical Industry.

Molecular hydrogen generated by elemental magnesium supplementation alters rumen fermentation and microbiota in goats.

We tested the hypotheses that supplementation of a diet with elemental Mg increases ruminal dissolved H2 (dH2) in rumen fluid, which in turn alters rumen fermentation and microbial community in goats. In a randomised block design, twenty growing goats were allocated to two treatments fed the same basal diet with 1·45 % Mg(OH)2 or 0·6 % elemental Mg. After 28 d of adaptation, we collected total faeces to measure total tract digestibility, rumen contents to analyse fermentation end products and microbial groups, and measured methane (CH4) emission using respiration chambers. Ruminal Mg2+ concentration was similar in both treatments. Elemental Mg supplementation increased dH2 at 2·5 h post morning feeding (+180 %, P<0·001). Elemental Mg supplementation decreased total volatile fatty acid concentration (-8·6 %, P<0·001), the acetate:propionate ratio (-11·8 %, P<0·03) and fungal copy numbers (-63·6 %, P=0·006), and increased propionate molar percentage (+11·6 %, P<0·001), methanogen copy numbers (+47·9 %, P<0·001), dissolved CH4 (+35·6 %, P<0·001) and CH4 emissions (+11·7 %, P=0·03), compared with Mg(OH)2 supplementation. The bacterial community composition in both treatments was overall similar. Ruminal dH2 was negatively correlated with acetate molar percentage and fungal copy numbers (P<0·05), and positively correlated with propionate molar percentage and methanogen copy numbers (P<0·05). In summary, elemental Mg supplementation increased ruminal dH2 concentration, which inhibited rumen fermentation, enhanced methanogenesis and seemed to shift fermentation pathways from acetate to propionate, and altered microbiota by decreasing fungi and increasing methanogens.

Shifts in Rumen Fermentation and Microbiota Are Associated with Dissolved Ruminal Hydrogen Concentrations in Lactating Dairy Cows Fed Different Types of Carbohydrates.

BACKGROUND: Different carbohydrates ingested greatly influence rumen fermentation and microbiota and gaseous methane emissions. Dissolved hydrogen concentration is related to rumen fermentation and methane production. OBJECTIVES: We tested the hypothesis that carbohydrates ingested greatly alter the rumen environment in dairy cows, and that dissolved hydrogen concentration is associated with these changes in rumen fermentation and microbiota. METHODS: Twenty-eight lactating Chinese Holstein dairy cows [aged 4-5 y, body weight 480 ± 37 kg (mean ± SD)] were used in a randomized complete block design to investigate effects of 4 diets differing in forage content (45% compared with 35%) and source (rice straw compared with a mixture of rice straw and corn silage) on feed intake, rumen fermentation, and microbial populations. RESULTS: Feed intake (10.7-12.6 kg/d) and fiber degradation (0.584-0.692) greatly differed (P ≤ 0.05) between cows fed the 4 diets, leading to large differences (P ≤ 0.05) in gaseous methane yield (27.2-37.3 g/kg organic matter digested), dissolved hydrogen (0.258-1.64 µmol/L), rumen fermentation products, and microbiota. Ruminal dissolved hydrogen was negatively correlated (r < -0.40; P < 0.05) with molar proportion of acetate, numbers of fungi, abundance of Fibrobacter succinogenes, and methane yield, but positively correlated (r > 0.40; P < 0.05) with molar proportions of propionate and n-butyrate, numbers of methanogens, and abundance of Selenomonas ruminantium and Prevotella spp. Ruminal dissolved hydrogen was positively correlated (r = 0.93; P < 0.001) with Gibbs free energy changes of reactions producing greater acetate and hydrogen, but not correlated with those reactions producing more propionate without hydrogen. CONCLUSIONS: Changes in fermentation pathways from acetate toward propionate production and in microbiota from fibrolytic toward amylolytic species were closely associated with ruminal dissolved hydrogen in lactating dairy cows. An unresolved paradox was that greater dissolved hydrogen was associated with greater numbers of methanogens but with lower gaseous methane emissions.

Effects of Feeding Encapsulated Nitrate to Beef Cattle on Ammonia and Greenhouse Gas Emissions from Their Manure in a Short-Term Manure Storage System.

A study was conducted to investigate effects of feeding encapsulated nitrate (EN) to beef cattle on ammonia (NH) and greenhouse gas emissions from their manure. Eight beef heifers were randomly assigned to diets containing 0 (control), 1, 2, or 3% EN (55% forage dry matter; EN replaced encapsulated urea in the control diet and therefore all diets were iso-nitrogenous) in a replicated 4 × 4 Latin square design. Urine and feces collected from individual animals were reconstituted into manure and incubated over 156 h using a steady-state flux chamber system to monitor NH, methane (CH), carbon dioxide (CO), and nitrous oxide (NO) emissions. Urinary, fecal, and manure nitrate (NO)-N concentration linearly increased ( < 0.001) with feeding EN, and urinary urea concentration tended to be lower ( = 0.078) for EN versus Control. The hourly emissions of NH, CO, and NO (mg head h) were not affected, although NH emission rates tended to be lower ( = 0.070) for EN compared with Control at 0 to 12 h. Cumulative NH, CO, and NO emissions over 156 h were not affected, but CH emissions were less (4.5 vs. 7.4 g head; = 0.027) for EN compared with Control. In conclusion, although NH emissions were initially lower for EN manures, total NH emitted over 156 h was not affected. Dietary EN lowered CH emissions from manure, and, despite greater NO concentrations in EN manure, NO emissions were not affected in this short-term incubation.

Evaluation of Different Yeast Species for Improving In vitro Fermentation of Cereal Straws.

Information on the effects of different yeast species on ruminal fermentation is limited. This experiment was conducted in a 3×4 factorial arrangement to explore and compare the effects of addition of three different live yeast species (Candida utilis 1314, Saccharomyces cerevisiae 1355, and Candida tropicalis 1254) at four doses (0, 0.25×10(7), 0.50×10(7), and 0.75×10(7) colony-forming unit [cfu]) on in vitro gas production kinetics, fiber degradation, methane production and ruminal fermentation characteristics of maize stover, and rice straw by mixed rumen microorganisms in dairy cows. The maximum gas production (Vf), dry matter disappearance (IVDMD), neutral detergent fiber disappearance (IVNDFD), and methane production in C. utilis group were less (p<0.01) than other two live yeast supplemented groups. The inclusion of S. cerevisiae reduced (p<0.01) the concentrations of ammonia nitrogen (NH3-N), isobutyrate, and isovalerate compared to the other two yeast groups. C. tropicalis addition generally enhanced (p<0.05) IVDMD and IVNDFD. The NH3-N concentration and CH4 production were increased (p<0.05) by the addition of S. cerevisiae and C. tropicalis compared with the control. Supplementation of three yeast species decreased (p<0.05) or numerically decreased the ratio of acetate to propionate. The current results indicate that C. tropicalis is more preferred as yeast culture supplements, and its optimal dose should be 0.25×10(7) cfu/500 mg substrates in vitro.

Rumen development process in goats as affected by supplemental feeding v. grazing: age-related anatomic development, functional achievement and microbial colonisation.

The aim of the present study was to describe age-related changes in anatomic, functional and microbial variables during the rumen development process, as affected by the feeding system (supplemental feeding v. grazing), in goats. Goats were slaughtered at seven time points that were selected to reflect the non-rumination (0, 7 and 14 d), transition (28 and 42 d) and rumination (56 and 70 d) phases of rumen development. Total volatile fatty acid (TVFA) concentration (P= 0·002), liquid-associated bacterial and archaeal copy numbers (P< 0·01) were greater for supplemental feeding v. grazing, while rumen pH (P< 0·001), acetate molar proportion (P= 0·003) and solid-associated microbial copy numbers (P< 0·05) were less. Rumen papillae length (P= 0·097) and extracellular (P= 0·093) and total (P= 0·073) protease activity potentials in supplemented goats tended to be greater than those in grazing goats. Furthermore, from 0 to 70 d, irrespective of the feeding system, rumen weight, rumen wall thickness, rumen papillae length and area, TVFA concentration, xylanase, carboxymethylcellulase activity potentials, and microbial copy numbers increased (P< 0·01) with age, while the greatest amylase and protease activity potentials occurred at 28 d. Most anatomic and functional variables evolved progressively from 14 to 42 d, while microbial colonisation was fastest from birth to 28 d. These outcomes suggest that the supplemental feeding system is more effective in promoting rumen development than the grazing system; in addition, for both the feeding systems, microbial colonisation in the rumen is achieved at 1 month, functional achievement at 2 months, and anatomic development after 2 months.

Effects of essential oils from medicinal plants acclimated to Benin on in vitro ruminal fermentation of Andropogon gayanus grass.

BACKGROUND: Plants from West Africa commonly used in both human and veterinary medicine contain various secondary metabolites. However, their potential in mitigating ruminal methane production has not been explored. This study examined the effects of seven essential oils (EOs) from plants acclimated to Benin at four dosages (100, 200, 300 and 400 mg L(-1)), on in vitro rumen microbial fermentation and methane production using Andropogon gayanus grass as a substrate. RESULTS: Compared to control, Laurus nobilis (300-400 mg L(-1) ), Citrus aurantifolia (300-400 mg L(-1)) and Ocimum gratissimum (200-400 mg L(-1)) decreased (P < 0.05) methane production (mL g(-1) DM) by 8.1-11.8%, 11.9-17.8% and 7.9-30.6%, respectively. Relative to the control, reductions in methane (mL g(-1) DM) of 11.4%, 13.5% and 14.2% were only observed at 400 mg L(-1) for Eucalyptus citriodora, Ocimum basilicum and Cymbopogon citratus, respectively. These EOs lowered methane without reducing concentrations of total volatile fatty acids or causing a shift from acetate to propionate production. All EOs (except M. piperita) reduced (P < 0.05) apparent dry matter (DM) disappearance of A. gayanus. CONCLUSIONS: The current study demonstrated that EOs from plants grown in Benin inhibited in vitro methane production mainly through a reduction in apparent DM digestibility.

Galyean appreciation club review: a holistic perspective of the societal relevance of beef production and its impacts on climate change.

This article provides a science-based, data-driven perspective on the relevance of the beef herd in the U.S. to our society and greenhouse gas (GHG) contribution to climate change. Cattle operations are subject to criticism for their environmental burden, often based on incomplete information disseminated about their social, economic, nutritional, and ecological benefits and detriments. The 2019 data published by the U.S. Environmental Protection Agency reported that U.S. beef cattle emitted 22.6% of the total agricultural emissions, representing about 2.2% of the total anthropogenic emissions of CO2 equivalent (CO2e). Simulations from a computer model developed to address global energy and climate challenges, set to use extreme improvements in livestock and crop production systems, indicated a potential reduction in global CO2e emissions of 4.6% but without significant enhancement in the temperature change by 2030. There are many natural and anthropogenic sources of CH4 emissions. Contrary to the increased contribution of peatlands and water reservoirs to atmospheric CO2e, the steady decrease in the U.S. cattle population is estimated to have reduced its methane (CH4) emissions by about 30% from 1975 to 2021. This CH4 emission deacceleration of 2.46 Mt CO2e/yr2 might be even more significant than reported. Many opportunities exist to mitigate CH4 emissions of beef production, leading to a realistic prospect of a 5% to 15% reduction in the short term after considering the overlapping impacts of combined strategies. Reduction strategies include feeding synthetic chemicals that inactivate the methyl-coenzyme M reductase (the enzyme that catalyzes the last step of methanogenesis in the rumen), red seaweed or algae extracts, ionophore antibiotics, phytochemicals (e.g., condensed tannins and essential oils), and other nutritional manipulations. The proposed net-zero concept might not solve the global warming problem because it will only balance future anthropogenic GHG emissions with anthropogenic removals, leaving global warming on a standby state. Recommendations for consuming red meat products should consider human nutrition, health, and disease and remain independent of controversial evidence of causational relationships with perceived negative environmental impacts of beef production that are not based on scientific data.

This article aims to provide data-driven information about the relevance of the U.S. beef cattle herd to our society and its greenhouse gas (GHG) contribution to climate change. The Environmental Protection Agency reported that U.S. beef cattle emitted 22.6% of the total agricultural emissions, representing about 2.2% of the total anthropogenic emissions of carbon dioxide equivalent (CO2e). Although the GHG contribution of the U.S. beef cattle production is small, there are many opportunities to reduce enteric methane emissions from beef cattle, with realistic estimates of a 5% to 15% reduction. However, net-zero emissions will be challenging to achieve for beef production. Considering the relatively minor contribution of beef cattle production to GHG emissions, other sources with a greater contribution to GHG emissions should be a much higher priority for mitigation as they would have a more substantial impact on slowing global warming. Recommendations by health professionals for consuming red meat products should consider human nutrition, health, and disease and remain independent of perceived negative environmental impacts of beef production that are not based on scientific data.

Effect of Metabolizable Protein Supply on Milk Performance, Ruminal Fermentation, Apparent Total-Tract Digestibility, Energy and Nitrogen Utilization, and Enteric Methane Production of Ayrshire and Holstein Cows.

In North America, the nutrient requirements of dairy cattle are predicted using the Cornell Net Carbohydrate and Protein System (CNCPS) or the National Research Council (NRC). As Holstein is the most predominant dairy cattle breed, these models were developed based on the phenotypic, physiological, and genetic characteristics of this breed. However, these models may not be appropriate to predict the nutrient requirements of other breeds, such as Ayrshire, that are phenotypically and genetically different from Holstein. The objective of this study was to evaluate the effects of increasing the metabolizable protein (MP) supply using CNCPS on milk performance, ruminal fermentation, apparent total-tract digestibility, energy and N utilization, and enteric methane production in Ayrshire vs. Holstein lactating dairy cows. Eighteen (nine Ayrshire; nine Holstein) lactating cows were used in a replicated 3 × 3 Latin square design (35-d periods) and fed diets formulated to meet 85%, 100%, or 115% of MP daily requirement. Except for milk production, no breed × MP supply interaction was observed for the response variables. Dry matter intake (DMI) and the yields of energy-corrected milk (ECM), fat, and protein were less (p < 0.01) in Ayrshire vs. Holstein cows. However, feed efficiency and N use efficiency for milk production did not differ between the two breeds, averaging 1.75 kg ECM/kg DMI and 33.7 g milk N/100 g N intake, respectively. Methane yield and intensity and urinary N also did not differ between the two breeds, averaging 18.8 g CH4 /kg DMI, 10.8 g CH4 /kg ECM, and 27.6 g N/100 g N intake, respectively. Yields of ECM and milk protein increased (p ≤ 0.01) with increasing MP supply from 85% to 100% but no or small increases occurred when MP supply increased from 100 to 115%. Feed efficiency increased linearly with an increasing MP supply. Nitrogen use efficiency (g N milk/100g N intake) decreased linearly (by up to 5.4 percentage units, (p < 0.01) whereas urinary N excretion (g/d or g/100 g N intake) increased linearly (p < 0.01) with an increasing MP supply. Methane yield and emission intensity were not affected by MP supply. This study shows that feed efficiency, N use efficiency, CH4 (yield and intensity), and urinary N losses did not differ between Ayrshire and Holstein cows. Energy-corrected milk yield and feed efficiency increased, but N use efficiency decreased and urinary N losses increased with increasing dietary MP supply regardless of breed. Ayrshire and Holstein breeds responded similarly to increasing MP levels in the diet.

Effect of physically effective neutral detergent fiber and undigested neutral detergent fiber on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract digestibility in finishing cattle.

This study evaluated the effects of physically effective neutral detergent fiber (peNDF) and undigested neutral detergent fiber (uNDF) on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract nutrient digestibility for finishing cattle. Six Simmental heifers (668 ± 28.4 kg BW) were used in a replicated 3 × 3 Latin square (21 d periods) balanced for carry-over effects. Treatments included a control (CON; Table 1) with no forage peNDF and minimal uNDF (peNDF: 0.0%, and uNDF: 4.88 ± 0.01; 95.15% barley grain, 4.51% vitamin and mineral supplement, and 0.34% urea on a DM basis). Pelleted wheat straw (PELL) was included at 10% of dietary DM by replacing barley grain to provide added uNDF but no forage peNDF (peNDF: 0.00%, and uNDF: 6.78 ± 0.02%). Finally, chopped wheat straw (STR) was included as a replacement for pelleted wheat straw to provide forage peNDF and uNDF (peNDF: 1.74 ± 0.06%, and uNDF: 6.86 ± 0.03%). Dry matter intake was not affected (P = 0.93) by treatments. Cattle fed CON spent less time ruminating (P = 0.010) and had less meals/d (P = 0.035) when compared with cattle fed STR, with those fed PELL being intermediate but not different from other treatments. Cattle fed CON had lesser ruminal pH (P = 0.020), and a greater duration that pH was < 5.5 (P = 0.020) as compared to cattle fed STR, with those fed PELL being intermediate but not different. Cattle fed CON and PELL had greater total short-chain fatty acid concentration (P = 0.003) and molar proportion of propionate (P < 0.001) when compared with cattle fed STR. Cattle fed STR had greater (P = 0.010) total ruminal pool size when compared with cattle fed CON and PELL. Cattle fed CON had greater (P = 0.043) duration between ruminal contractions when compared with cattle fed STR, with those fed PELL being intermediate. Cattle fed CON had greater serum amyloid A (P = 0.003) and haptoglobin (P < 0.001) concentration when compared with the other treatments. Cattle fed CON had greater dry matter (P < 0.001) digestibility when compared with the other treatments. In conclusion, inclusion of PELL and STR impacted eating behavior, but only STR affected ruminal fermentation, ruminal motility, systemic inflammation, and total tract nutrient digestibility in finishing cattle. These results are interpreted to suggest that the combination of peNDF and uNDF may be better than uNDF alone to adequately capture biological effects of NDF in high-concentrate diets.

Normally forages are included at minimal levels when formulating finishing cattle diets due to lower digestibility and higher operational and economic costs than concentrates. However, insufficient fiber may increase the risk of nutritional disorders such as ruminal acidosis, negatively impacting health, and consequently growth performance of feedlot cattle. An understanding of the minimum forage requirement and the constituent factors that best explain that requirement can help to promote health and performance while minimizing cost. The present study compared the effects of physically effective neutral detergent fiber (peNDF) and undigested neutral detergent fiber (uNDF) in concentrate-based finishing diets. Feeding more peNDF increased ruminating time and ruminal pH, but decreased time between ruminal contractions, total short-chain fatty acid concentration, and the molar proportion of propionate when compared with feeding a diet with minimal peNDF and uNDF. Responses to feeding uNDF with no peNDF were generally intermediate but not different from other treatments. In addition, feeding more peNDF decreased indicators of systemic inflammation and dry matter digestibility when compared with the diet with less peNDF or uNDF. In conclusion, peNDF, or at least the combination of peNDF and uNDF may be better than uNDF alone to stimulate rumination and ruminal motility, thereby stabilizing ruminal pH. Using both peNDF and uNDF may be useful in characterizing the value of fiber in finishing diets fed to feedlot cattle.

Effect of forage types differing in undigested neutral detergent fiber concentration and forage inclusion rate on reticulo-ruminal motility and fermentation, total tract barrier function, and blood metabolites of finishing beef heifers.

This study evaluated the effects of forages (BarS vs. STR) that differ in the uNDF concentration and FI rate on ruminal fermentation, total tract barrier function, reticulo-ruminal motility, and blood metabolites of beef heifers. Six ruminally cannulated Hereford × Simmental heifers (699 ± 69.1 kg BW) were used in a 6 × 6 Latin square (26 d periods) with a 2 × 3 factorial treatment arrangement. However, 1 heifer was removed from the study after period 2 due to health problems unrelated to treatment, resulting in an incomplete 6 × 6 Latin square design. Barley grain-based diets were formulated using BarS or wheat STR to alter uNDF (7.1% vs. 8.5% DM) with FI rates of 5%, 10%, or 15% of DM. There were limited interactions between the forage type and FI. DM intake was not affected (P ≥ 0.10) by forage type or FI. Use of STR vs. BarS increased uNDF intake (P < 0.001). Increasing FI increased (P < 0.001) uNDF intake for those fed 15% forage. Ruminal pH was not affected (P ≥ 0.10) by forage type; however, cattle fed 5% FI had lesser (P = 0.017) mean ruminal pH and maximum pH (P = 0.018) than those fed 10% and 15% of forage. The total SCFA concentration was not affected by forage type (P = 0.84) but cattle fed the 5% FI rate had lesser (P < 0.001) molar proportion of acetate when compared with cattle fed 10% and 15% forage. Increasing the FI rate decreased the molar proportion of propionate (P < 0.001). Feeding STR relative to BarS decreased (P = 0.041) the reticulo-ruminal contraction duration. In contrast, cattle fed the 10% and 15% FI rates had a greater (P = 0.028) contraction frequency with lower (P = 0.048) contraction area than those fed 5% forage. Plasma glucose, serum insulin, and serum amyloid A were not affected by forage type or FI rate (P ≥ 0.10). Cattle fed 15% forage had lesser (P = 0.040) concentration of serum haptoglobin when compared with cattle fed 5% or 10% forage. In conclusion, forage type used to affect the dietary uNDF concentration, and FI rate act independently suggesting that the provision of STR to increase uNDF reduces reticulo-ruminal contraction duration and total tract permeability but may not affect ruminal pH. Increasing the FI increased dietary uNDF, stabilized ruminal pH, stimulated more frequent reticulo-ruminal contractions, and may decrease the permeability of the gastrointestinal tract and systemic inflammation.

As a strategy to improve performance, feedlot cattle are often fed diets containing a high proportion of grain with minimal forage. However, diets with insufficient fiber may predispose cattle to nutritional disorders, such as ruminal acidosis, which leads to poor performance and increases production costs. Given the growing concern regarding minimal fiber requirement, the present study was designed to investigate the effects of forages differing in undigested neutral detergent fiber (uNDF; barley silage [BarS] vs. straw [STR]) concentration and forage inclusion (FI) rate (5%, 10%, or 15% of dietary dry matter [DM]) on reticulo-ruminal motility and fermentation, total tract barrier function, and blood metabolites of beef cattle. The inclusion of STR increased uNDF intake and rumination rate, but decreased reticulo-ruminal contraction duration, with no effect on ruminal pH and total short-chain fatty acid (SCFA) concentration. Decreasing the FI rate decreased uNDF intake, ruminating time, ruminal pH, and reticular contraction frequency, but increased the molar proportion of propionate and concentration of serum haptoglobin. In conclusion, forage type and FI rate act independently suggesting that providing forages that increase dietary uNDF may stimulate the frequency of reticulo-ruminal contractions without affecting ruminal pH. However, increasing FI inadvertently increased dietary uNDF, stabilized ruminal pH, increased rumination time, stimulated ruminal contractions, and decreased indicators of systemic inflammation.

3-Nitrooxypropanol supplementation of a forage diet decreased enteric methane emissions from beef cattle without affecting feed intake and apparent total-tract digestibility.

Supplementation of ruminant diets with the methane (CH4) inhibitor 3-nitrooxypropanol (3-NOP; DSM Nutritional Products, Switzerland) is a promising greenhouse gas mitigation strategy. However, most studies have used high grain or mixed forage-concentrate diets. The objective of this study was to evaluate the effects of supplementing a high-forage diet (90% forage DM basis) with 3-NOP on dry matter (DM) intake, rumen fermentation and microbial community, salivary secretion, enteric gas emissions, and apparent total-tract nutrient digestibility. Eight ruminally cannulated beef heifers (average initial body weight (BW) ±â€…SD, 515 ±â€…40.5 kg) were randomly allocated to two treatments in a crossover design with 49-d periods. Dietary treatments were: 1) control (no 3-NOP supplementation); and 2) 3-NOP (control + 150 mg 3-NOP/kg DM). After a 16-d diet adaption, DM intake was recorded daily. Rumen contents were collected on days 17 and 28 for volatile fatty acid (VFA) analysis, whereas ruminal pH was continuously monitored from days 20 to 28. Eating and resting saliva production were measured on days 20 and 31, respectively. Diet digestibility was measured on days 38-42 by the total collection of feces, while enteric gas emissions were measured in chambers on days 46-49. Data were analyzed using the mixed procedure of SAS. Dry matter intake and apparent total-tract digestibility of nutrients (DM, neutral and acid detergent fiber, starch, and crude protein) were similar between treatments (P ≥ 0.15). No effect was observed on eating and resting saliva production. Relative abundance of the predominant bacterial taxa and rumen methanogen community was not affected by 3-NOP supplementation but rather by rumen digesta phase and sampling hour (P ≤ 0.01). Total VFA concentration was lower (P = 0.004) following 3-NOP supplementation. Furthermore, the reduction in acetate and increase in propionate molar proportions for 3-NOP lowered (P < 0.001) the acetate to propionate ratio by 18.9% as compared with control (4.1). Mean pH was 0.21 units lower (P < 0.001) for control than 3-NOP (6.43). Furthermore, CH4 emission (g/d) and yield (g/kg DMI) were 22.4 and 22.0% smaller (P < 0.001), respectively, for 3-NOP relative to control. Overall, the results indicate that enteric CH4 emissions were decreased by more than 20% with 3-NOP supplementation of a forage diet without affecting DM intake, predominant rumen microbial community, and apparent total-tract nutrients digestibility.

This study evaluated the effects of supplementing forage fed cattle with 3-nitrooxypropanol (150 mg/kg dry matter) on feed intake, rumen fermentation and microbial community composition, methane emissions, and nutrient digestibility. Eight ruminally cannulated beef heifers were used for the experiment. The results indicated that 3-nitrooxypropanol supplementation substantially reduced methane emissions without affecting feed intake and total-tract digestibility of nutrients.

Comparative analysis of macroalgae supplementation on the rumen microbial community: Asparagopsis taxiformis inhibits major ruminal methanogenic, fibrolytic, and volatile fatty acid-producing microbes in vitro.

Seaweeds have received a great deal of attention recently for their potential as methane-suppressing feed additives in ruminants. To date, Asparagopsis taxiformis has proven a potent enteric methane inhibitor, but it is a priority to identify local seaweed varieties that hold similar properties. It is essential that any methane inhibitor does not compromise the function of the rumen microbiome. In this study, we conducted an in vitro experiment using the RUSITEC system to evaluate the impact of three red seaweeds, A. taxiformis, Palmaria mollis, and Mazzaella japonica, on rumen prokaryotic communities. 16S rRNA sequencing showed that A. taxiformis had a profound effect on the microbiome, particularly on methanogens. Weighted Unifrac distances showed significant separation of A. taxiformis samples from the control and other seaweeds (p < 0.05). Neither P. mollis nor M. japonica had a substantial effect on the microbiome (p > 0.05). A. taxiformis reduced the abundance of all major archaeal species (p < 0.05), leading to an almost total disappearance of the methanogens. Prominent fiber-degrading and volatile fatty acid (VFA)-producing bacteria including Fibrobacter and Ruminococcus were also inhibited by A. taxiformis (p < 0.05), as were other genera involved in propionate production. The relative abundance of several other bacteria including Prevotella, Bifidobacterium, Succinivibrio, Ruminobacter, and unclassified Lachnospiraceae were increased by A. taxiformis suggesting that the rumen microbiome adapted to an initial perturbation. Our study provides baseline knowledge of microbial dynamics in response to seaweed feeding over an extended period and suggests that feeding A. taxiformis to cattle to reduce methane may directly, or indirectly, inhibit important fiber-degrading and VFA-producing bacteria.